Medical instruments (such as dental, pharmaceutical, veterinary, and mortuary devices) that are exposed to blood or other bodily fluids require thorough cleaning and microbial deactivation between each use. Medical instruments may be microbially deactivated by exposure to a gaseous or vaporous deactivating agent, such as vaporized hydrogen peroxide, during a microbial deactivation process. For a medical instrument to be successfully deactivated during a microbial deactivation process, all surfaces of the medical instrument must be exposed to a predetermined minimum concentration of vaporized hydrogen peroxide for a predetermined minimum period of time.
Some surfaces of medical instruments are difficult to expose to the vaporous deactivating agent because of the shape, i.e., geometry, of the instrument. For example, for instruments having lumens, it is difficult to expose the inner surfaces of the lumens to the vaporous deactivating agent. As a result, a microbial deactivation process may not be effective because such surfaces have not been successfully deactivated by appropriate exposure to the vaporous deactivating agent.
A process challenge device (also commonly referred to as a “test pack”) is designed to simulate an item being deactivated and to constitute a defined challenge to the microbial deactivation process. In order to assess the effectiveness of a microbial deactivation process a process challenge device (PCD) is placed within a deactivation chamber along with the instruments being deactivated. A PCD includes a housing and a biological indicator (BI) and/or a chemical indicator (CI), that are placed inside the housing. The housing includes internal passageways that create a challenge to the microbial deactivation process that is representative of the most difficult item to deactivate in a load. Following completion of a microbial deactivation process, the biological indicator and/or chemical indicator are analyzed in a known manner to determine the effectiveness of the microbial deactivation process.
A conventional PCD housing includes a narrow internal passageway formed therein that has an open end and a closed end. The open end of the passageway is in fluid communication with a region external to the housing. A BI and/or CI is disposed at the closed end of the passageway. During a microbial deactivation process, vaporized deactivating agent can travel from the region external to the housing, along the passageway, and to the BI and/or CI located at the closed end of the passageway.
One problem with existing PCD housings is that the passageway leading to the BI and/or CI can become partially or fully blocked, thereby causing the BI and/or CI to provide inaccurate results concerning the effectiveness of the microbial deactivation process. The passageway within the housing can become blocked as the result of several conditions. For example, condensation of the vaporous deactivating agent within the passageway can result in blockage of the passageway. The passageway can also become blocked when the walls defining the passageway collapse or are drawn into the passageway in response to pressure changes during the microbial deactivation process. For example, a known PCD housing includes a layer of flexible plastic film that defines a wall of the passageway. During a deactivation process, the flexible plastic film may collapse or be drawn into the passageway when the PCD is exposed to large changes in pressure, thereby reducing the diameter of the passageway. A PCD having a passageway with a reduced diameter provides a challenge greater than the most difficult item to deactivate in the load. Accordingly, the BI and/or CI may not provide accurate results.
Another problem with existing PCD housings is that the BI and/or CI of the PCD may not be exposed to the same concentration of vaporous deactivating agent (e.g., vaporized hydrogen peroxide) as the surfaces of the instruments being deactivated. It is believed that this inconsistency results from inadequate circulation of the vaporous deactivating agent within the PCD housing, as compared to the circulation of vaporous deactivating agent within the item (e.g., a lumened instrument) being deactivated.
The present invention overcomes these and other problems by providing a PCD that maintains a challenge to microbial deactivation that is representative of the most difficult item to deactivate in a load and can provide fluid circulation therein to provide appropriate exposure to a biological and/or chemical indicator.